Morphological, anatomical, geographical and ecological data were utilized in a
systematic study of the grass- genus Cymbopogon. The genus is largely confined
to the Old World tropics and subtropics; C. densiflorus has become naturalized in
the New World (Brazil) and C. refractus in the Pacific Islands. A taxonomic
account is presented in which 55 species are recognized and placed in 5 series
which have definite geographical distribution: ser. Cymbopogon (from West Africa
to India), ser. Rusae (from Africa to Indo-China), ser. Citrati (Africa, Asia and
Australia), ser. Proceri (Australia) and ser. Refracti (Australia). Ser. Proceri
and ser. Refracti are described for the first time, as is C. goeringii var. hongkong-
ensis. In this study three new combinations are proposed, one species is excluded
from Cymbopogon, while two species and four varieties are considered of uncertain
status because type material was not available. One natural hybrid between
C. bombycinus and C. ambiguus is recognized. Full descriptions of species and key
to the series and species are given. Two new chromosome counts of C. procerus
and C. bombycinus were reported so that data are now available for 22 species, which
are all on the polyploid series 2n = 20, 40, 60.